DEVELOPMENTS: The financial problems of Tesdata deepened in the fiscal year ended Dec. 31, although recent steps by the firm's management have improved the outlook for the current year. The company's revenue was off 50 percent last year, and net loss increased 46 percent in 1985. Management attributes the poor financial performance to the impact of lost income as the result of selling off its European operations late in 1984. The division had provided about 40 percent of Tesdata's revenue. Tesdata also encountered increased operating costs in the introduction of a new version of the company's data-communications network.

To accommodate reduced revenue last year, the company trimmed operations to bring its break-even income figure from $11 million to $6 million. This was achieved by laying off personnel, closing field offices, closing a Sunnyvale, Calif., operation and consolidating manufacturing and administrative functions in offices in Herndon. #91. BIOTECH RESEARCH LABORATORIES INC.

DESCRIPTION: Biotech Research Labs employs methods such as gene splicing and cell fusion to conduct biomedical research and product development. It also manufactures and sells biomedical products such as cell cultures and viral diagnostic kits, and provides laboratory services.

DEVELOPMENTS: Biotech Research Laboratories is thriving on its AIDS-related products and services. Total revenue increased 82 percent in 1985 compared with the year before, fueled primarily by sales of a test to detect antibodies to the virus believed to cause AIDS (acquired immune deficiency syndrome). The company's net loss also grew slightly, largely because of product development expenses.

Sales of the AIDS antibody tests accounted for about one-third of the company's total revenue. Profits were limited because the tests were sold at cost to the company's partner, E. I. duPont de Nemours & Co., for clinical trials conducted before October, when the two companies received federal approval to market the product. The tests were sold at a profit after October.

Biotech Research also developed a "dip-stick" test for AIDS antibodies, designed for use with small blood samples, and a "Western Blot" test, a more sophisticated form of AIDS antibody test used to confirm results of the more widely used test. The company also established a clinical reference laboratory to perform Western Blot tests for blood centers and other clients.

The demand for the AIDS antibody test helped propel the company's transformation from a research firm into a product manufacturing company. Product sales increased to 50 percent of total revenue in 1985 from 27 percent in 1984.

In June of last year, Biotech Research joined with a group of investors to form Diagnostic Biotechnology Pte. Ltd., a Singapore-based venture designed to produce diagnostic products to meet the needs of the Asian market. #92. SUTRON CORP.

DEVELOPMENTS: Sutron revenue increased 9 percent in the fiscal year ended Dec. 31, but profits dropped 60 percent over the prior year. Management attributed the sharp drop in net income to increased investment in research and development to develop future products and services. Company officials declined to offer specific information about future directions for Sutron but noted that it recently leased an additional 10,000 square feet of space to keep its long-range growth plan on schedule. #93. D.C. TRADING & DEVELOPMENT CORP.

DESCRIPTION: D.C. Trading & Development, formerly the D.C. Transit System Inc., is primarily a real estate holding company. D.C. Transit operated the city's bus and streetcar system before the District government acquired it in 1973. Since then, D.C. Trading and Development has been involved in managing real estate, including substantial portions of the old right-of-way held by the corporation after disposition of the transit system. The transfer of the system has created a tangle of lawsuits related to various claims and liabilities that continue to be pressed against the company.

D.C. Trading & Development has taken steps to diversify in recent years and operates a travel subsidiary, DCT Travel Inc., and a high-tech manufacturing and research center in Northeast Washington. The company also holds rights to airline routes in the Caribbean under a nonoperating subsidiary called Trans Carib Air Inc.

DEVELOPMENTS: A 25 percent decline in revenue in the fiscal year that ended Dec. 31 was carried directly to the company's bottom line and reflected as a $1.9 million turnaround in net income -- from a gain of $1.2 million in fiscal 1984 to a loss of more than $700,000 in fiscal 1985.

The company's operating expenses rose sharply last year as 12 diversified machining centers, all totally computer-controlled, were integrated into the company's DCTECH Research Center and prepared for approval by various branches of the Department of Defense and prime contractors bidding on work for DOD and the National Aeronautics and Space Administration. The company also added manufacturing and marketing personnel to the high-tech center as operations started there in the last quarter of 1985.

D.C. Trading & Development's financial statements continue to be shadowed by a qualifying statement from its independent accountant, noting that the outcome of litigation pending against the company is uncertain. No reserves or other provisions have been made by the firm should an adverse decision result. The accountant's statement notes that the amount of potential court-directed liabilities "could be substantially in excess of the company's stockholders' equity, and therefore could have adverse effects as to preclude the company's continuance as a viable concern." #94. ISOMET CORP.

DESCRIPTION: Isomet makes laser accessory components and equipment from synthetic crystals grown in its facilities. It also conducts research and development in laser technology for the government and other contractors.

DEVELOPMENTS: Isomet, on the strength of several new product announcements in 1985, increased revenue 38 percent in 1985. However, because of up-front marketing and promotion expenses related to new product introductions, the company reported net losses 2 1/2 times greater than in 1984. In addition, the company encountered higher than expected costs in turning out the first production models of the new products.

The products brought to market last year by Isomet include a laser-based marking system and a laser color-scanning device for use in the printing industry.

Isomet's backlog of firm orders at yearend was put at $3 million, up substantially from the $2.3 million backlog at the end of 1984.